Stents, grafts, stent-grafts, vena cava filters, vascular implants, and similar implantable medical devices, collectively referred to hereinafter as stents, are radially expandable endoprostheses which are typically intravascular implants capable of being implanted transluminally and enlarged radially after being introduced percutaneously. Stents are typically mounted onto a catheter assembly for deployment within a body lumen. Stents may be implanted in a variety of body lumens or vessels such as within the vascular system, urinary tracts, bile ducts, etc. Stents may be used to reinforce body vessels and to prevent restenosis following angioplasty in the vascular system. They may be self-expanding, such as a nitinol shape memory stent, mechanically expandable, such as a balloon expandable stent, or hybrid expandable.
Prior to delivery a stent or stents may be retained on a portion of the delivery catheter by crimping the stent onto the catheter, retaining the stent in a reduced state about the catheter with a removable sheath, sleeve, sock or other member or members, or by any of a variety of retaining mechanisms or methods. Some examples of stent retaining mechanisms are described in U.S. Pat. Nos. 5,681,345; 5,788,707; 6,066,155; 6,096,045; 6,221,097; 6,331,186; 6,342,066; 6,350,277; 6,443,880; 6,478,814 and U.S. patent application Ser. No. 09/664,268 entitled Rolling Socks and filed Sep. 18, 2000.
In some systems for the delivery of a self-expanding stent, the stent is deployed by a pull back sheath system. When the stent is constrained within the system, the stent is exerting a force onto the inside diameter (ID) of the outer shaft or pull back sheath. The frictional interface between the stent and sheath may cause the sheath to negatively interact with the stent as the sheath is retracted during deployment. Lubricious coatings may be used to aid in reducing the frictional interface between the stent and sheath. In some cases, particularly those involving longer stents and thus greater frictional forces, the forces may be to great for the lubricant to compensate for. As a result, in some systems the frictional forces involved will prevent the catheter from being capable of properly deploying a stent of a desired length.
Excess frictional interaction between the stent and sheath is of particular concern in systems deploying a stent that incorporates one or more therapeutic coatings thereon, as the coatings may be adversely affected by the frictional interface between the sheath and stent, particularly during sheath retraction.
The present invention seeks to address these and/or other problems by providing catheter assemblies with a variety of embodiments and features which improve sheath retraction and stent deployment characteristics.
All U.S. patents, applications and all other published documents mentioned anywhere in this application are incorporated herein by reference in their entirety.
Without limiting the scope of the invention a brief summary of some of the claimed embodiments of the invention is set forth below. Additional details of the summarized embodiments of the invention and/or additional embodiments of the invention may be found in the Detailed Description of the Invention below.
A brief abstract of the technical disclosure in the specification is provided as well only for the purposes of complying with 37 C.F.R. 1.72. The abstract is not intended to be used for interpreting the scope of the claims.